Creating a sketch for building a light house made of wood

[derNiwi]

Hi there,

I started with several tutorials and build small things with FreeCAD yet. That were good lessons to start with FC.

Now I have the idea to build a light house with wood and construct the most parts with FreeCAD, using a spread sheet to make it possible to resize the tower. I like to build the single wooden parts and let FreeCAD calculate some meassurements and angles.

My plan is to start with a octagonal base, each side is 100mm. The upper part is about 1000mm above and each side is 75mm. Then I need eight planks as wall. And this is my first problem. I can build the sketch for the base and the sketch for the upper part. But the planks are not just square blocks. And I need to connect the upper edge of a plank to the upper octagon, let FC calculate the angles. Also a plank should be three dimensional.

Has anyone a tutorial how to build such a construction?

I add my current file, all three sketches are only two-dimensional at the moment since I don't know how to build the connections between the parts.

Best regards
Nils

[Willem]

Hi Nils, you already did some tutorials and I do not know what your problems are exactly. You also want your dimensions in a spreadsheet, here are some tips
- give the values in the spreadsheet an ALIAS, this is a name you can call in your dimensions with EXPRESSIONS,
- Make a sketch of the plank under the desired angle, I did this with expressions to sketches with the base and upper octagons. Give the pad an enormous width
- Make another sketch with a triangle with the angle of 45 degrees and pad this with the hight
- Make a BOOLEAN COMMON operation between the two shapes and it will make one side of your lighthouse
- Make an ARRAY to complete the lighthouse

If you want more information about some of these steps please ask and I will give a more detailed description

[bejant]

Hi Nils, and welcome here!

What version of FreeCAD are you using?
viewtopic.php?f=3&t=2264

What you want to do is really not difficult once you learn how it is done but I can't recall anyone wanting to model a lighthouse. We have had several wine cask or beer keg help topics and it seems to me that the wine cask staves roughly resemble the geometry of your lighthouse sides. You will get better replies soon but (scratch that, Willem gave a better reply while I was fiddling around) here are some threads to read, and they have FreeCAD models to examine:

https://forum.freecadweb.org/viewtopic.php?f=3&t=10025
https://forum.freecadweb.org/viewtopic.php?f=3&t=16977
https://forum.freecadweb.org/viewtopic.php?f=24&t=17004

blue and strike-through = edit.

[Willem]

Hi again,

another way to do the lighthouse is to use the upper and lower sketch for making the top and bottom side of one plank
create a plank with a loft
use an array to make the 8 sides

[chrisb]

I add my current file

A remark on your upload: You should not zip your FreeCAD file before uploading (so the Forum Guidelines tell you), because it doesn't shrink the file - in the opposite, yours became larger - and it is more annoying steps before opening the file.

[derNiwi]

Hello,

thank you for your help.

The model I'd like to build is not the main problem, also I don't ask for building a lighthouse for me.

My problem ist to build a blank which is not perpendicular to the ground because the upper part is smaller than the lower part. So I need to have an angle lower than 90°, depending on the height of the complete tower. I thought it should be possible to create a 3d plank and let FC calculate the angles for me so I get a part list which I can print later and use a piece of wood and a saw to cut this plank (and also the other parts...).

I know that some people create exploded assembly draws which will help later for building.

Regards,
Nils

PS: I'm using FreeCad 0.16.6706
PPS: I tried to use the original file but I couldn't select the .fcstd file.

[Willem]

Hi, in drawing lighthouse02 it is possible to make a dimension in construction mode of the plank.
A CLONE can be made in the draft workbench and this clone can be rotated back to XYZ coordinates
A drawing can be made with the CLONE as object for the drawing
You have to install the dimensioning workbench
With this workbench you can finish the drawing

Plank.svg

(135.02 KiB) Downloaded 234 times

[derNiwi]

Hi,

I played a little bit with FreeCAD and your ideas. I tried several methods but only the "loft" and the cut through the piece of cake are usefull.

Aditionally I used the spread sheet, formulas for the calculations etc. so it is possible to change the dimensions quickly. I'm still far away from the result I have in mind but a big step closer to it. I see I have still much to learn.

Thank you for your help, I attached the current test file with a page displaying the dimensions.

Regards,
Nils

[derNiwi]

Hi there,

thanks to all for helping. I have updated my "project" a little bit, focused on using the spread sheet for fast modifying the light house.

I know that this is not a model for having a detailed light house but that is not my goal. I just need a model for seeing the proportions.

Have a nice weekend
Nils

[Willem]

Hi Nils,

it is pleasant to see you made a good progress in using FreeCad, When your wooden lighthouse is ready please post a photo of it